Spark-plug for explosive-engines.



M. T. MINOGUE.

SPARK PLUG FOR EXPLOSIVE ENGINES.

APPLICATION FILED IUNE 8 l916.

Patentd Sept. 4, 1917.

4 6 7 AJ W5. E

UNITED MARTIN T, MINGUE, GF

nILl-LDELPHIA, PENNSYLVANIA.

SPARK-PLUG FCE; EXPLOSIVE-ENGINES.

Speccaton of Eetters atent.

Fatented Sept. 4, 1917.

Application filed .Tune 8, 1916. Seri-el No. 102,482.

To all whom t may concern.'

Be it known that MARTIN T. llf'lrnoerm, av citizen of the United States,residing in Philadelphia, Pennsylvania, have iniiented certainlmprovements in Spark-Plugs for llxplosive-Engines, of which thefollowing is aspecification.

One object of my invention is to so construct a spark plug for explosiveengines as to provide for a more erective insulation than usual betweenthe electrode or electrodes of the plug and the casing of the engine, a.further object being to permit of the convenient employment ofdii'lerent insulating bodies in one and the same plug, and a stillfurther object being to provide convenient connections between theelectrodes of the plug and the conducting wires thereof.

In the accompanying drawing- Figure 1 is a transverse section, on anenlarged scale, of ay spark plug constructed. in accordance -with myinvention;

Figs. 2 and 3 are detached persijiective views of elements of said plug,and

Figs. 4 and 5 are transverse sections illustrating modified forms otplug embodying certain features of my invention.

The-body of the plug is composed wholly or almost Wholly of insulatingniateriah'tlnit form of plug shown in Fig. 1 ol: the drawing havinginner and outer insulating members 1 and 2 oil dierent qualities orinsulating material, for instance, the inner member l, Which may forconvenience be referred to as the primary l member, may well be composedof porcelain or other refractory material yof high dielectricproperties, while the outer member, which may be regarded as thesecondary member, can conveniently be composed ot' tough material whichopposes more resistance to fracture than the porcelain member l..

The secondaryT insulating member 2 is duced in 'diameter at its lowerend tor in, tion into the shell of the `valve chest or other convenientportion of the engine cylinder, and, if the material of said secondaryinsulating member is not such as to warrant the direct formation thereonof a 'thread whereby it may be screwed into an internally threadedopening in said casing, the reduced portion of said secondary member isproyided with a surrounding and externally threaded tubular nipple 8 ofmetal for this purpose.

ln order to insure the secure connection of this nipple to saidsecondary insulating, member, it projects into the body of insulatingmaterial and is molded into the same while said material is in aplastic. state, the material tluu'efore passing through perforations #l(Fig. 2) in the embedded portion of the nipple and iirmly keying thesame to the insulating member 2, as shown in Fig. 1. The ilariniaryinsulating member 1 may also be tirmly secu red to the secondaryinsulating member by molding it therein while the material oi saidsecondary insulating member is plastic, suitable shoulders, spurs, orbarbs 5 being, it desired, formed upon the yexterior of the primarymember 1 in order to insure a firmer hold of the secondary memberthereon after it has been subjected to the hardening process.

Contained in the primary member 1 are a pair oi" longitudinal electrodesG and 7 whose inner ends project beyond the inner end et said primarymember, and, if the plug is to be used in series with another plug, areso disposed in respect to one another as to Ylform a spark gap betweenthem. YWhen, however, the shell of the engine is connected to one poleof the generator, the electrode T may be dispensed with and the. sparkgap may be formed between the inner end or the electrode G and anelectrode projectino' from the nipple 3, as shown by dotted lines at S,in Fig. 1, or otherwise electrically connected with the casing of theengine. i

Resting upon the outer end of the secondary insulating member Q ot' theplug is a c y lindrica-l cap 2 also, by preference, of similarinsulating material, and the upper end of the electrode G passes freelythrough central openings in washers 9, 10 and 11v disposed one aboveanother at the outer end oi? said cap Qu, said electrode heilig threadedfor the reception of aV confining nut 12/ whereby said washers 9, 10 andl1 are clamped together and to the outer end of the cap 2, anotherconining nut 13 being also adapted to the threaded outer end or' theelectrodo G so as to secure the conducting wire thereto.

The washer 9 bea-rs upon the upper end of the cap 2, and, between thewashers 10 and 11, which are composed of insulating material, isconlined the upper end of an angularly bont spring finger l-l, whoseupper end is forked, as shown at l5 in Fig. 3, so as to straddle theelectrode, and whose lower end is likewise forked, as shown at 16 inFig. 8, so as to engage with the grooved portion of a plunger 17 whichis free to move back and forth through a notch in the side of the cap 2and through a coinciding recess in one side of the insulating member 1,said plunger being Inormally pressed inwardly by the spring finger laand being thereby maintained in contact with the upper end of theelectrode 7 projecting into said recess or with a plug 18 containedwithin said` recess and engaged by the upper end of said electrode,asshown in Fig. 1.

-The electrode 7 and the contact device therefor just described are onlyemployed in case the spark plug is being used as a series plug and insuch case the wire communicating with lthe second pole of the generatormay be secured to the plunger 17 by means of a binding screwl 19.

Yhen desired the tap and all of the parts carried thereby can be readilyremoved from the plug upon Erst removing the nuts 12 and In some'casesit may be advisable also to remove the primary insulating member 1 ofthe plug from the secondary insulating member 2 of the same, and in suchease the' construction lshown in Fig. 4 may be adopted, that is to say,the insulating member 2 may be enlarged in diameter' at its inner end.so as to form a shoulder 25 providing a seat for a gasket 26 interposedbetween the same and a shoulder 27 on the primary insulating member 1 ofthe plug. When, therefore, upward draft upon the electrode 6 is releasedthe primary insulating member 1 can be readily removed through the innerend of the plug.

Then the nipple 3 is used the insulating members 1 and 2 extendcompletely through the same,consequently there is no possibility of ashort circuit in case of fracture of the primary insulating' member,within said sleeve, or even of breaks in both primary and secondaryinsulating members in the external portion of the plug and nopossibility of- ,a shortv circuit between a conductor and the outer faceof'that portion of the plug which is outwardly beyond the engine casing,and in this respect my invention overcomes a serious objection toordinar; spark plugs in which a single insulating ody has a surroundingcasing of metal whereby 'it is secured to the casing of the engine,since, in such plugs, `breaks in the continuity of the insulating bodyalmost invariably cause short circuits between the contained electrodeand said outer shell.

In that embodiment of my invention. shown in Fig. 5 the primary member lis enveloped by the outer or secondary member 2 except as to its innerend, andopposite recesses 20, separated by a wall of insulatingmaterial, are formt in the upper end of said primary member, each ofthese recesses receiving the upper end of an electrode which engages aplug 2l having a threaded stem to which outward draft may be imparted bya nut on4 the outside of the insulating member 2, as shown in connectionwith the electrodes in Fig. 5, or, when the plug carries 1but a singleelectrode, it may have but a single bore and recess for the reception ofthe same.

I claim:

l. In a spark plug for explosive engines, a mass of insulating materialconstituting an integral part of the plug, said mass surrounding theelectrode and extending to the casing from which the plug projects,whereby the outer surface of that part of the plug which projects beyondthe casing is composed wholly of insulating n'iatcrial.

2. In a spark plug for explosive engines, the combination'of a. primaryor internal insulator surrounding the electrode, with a secondary orexternal insulator surroundings,l said primary insulator and consistingof a mass of insulating material extending to the surface of thatportion of the engineI casing to 'which the plug is applied, wherebyi itnstitutes the outer surface of all that por ion of the plug whichprojects beyond the engine casing.

3. In a spark plug for explosive engines, a mass of insulating materialconstitutingI the external portion of the plug and extending to theengine casing, in combination with a threaded nipple for screwing intosaid casing, all that portion of said nipple which projects beyond thecasing being embedded in and surrounded by said mam of insulatingmaterial.

e. A spark plug for explosive engines, said plug having aninsulatingbody and a tubular nipple surrounding the'inner end thereof and having aperforated portion embedded in said body of insulating material whichalso fills said perforations.

5. .A spark plug for explosive engines,

'said plug consisting of a primary insulating member of porcelain and asecondary insulating member surrounding the same and composed ofmaterial which is tough and will resist fracture, said secondary memberbeing molded directly onto the primary member. l

6. A spark plug having an insulating member with two electrodes, oneextending through the outer end thereof, a plunger passing laterallyinto the member and in electrical connection with the other electrode,and a spring finger carrying said plunger.

7. The combination, in a spark plug for explosive engines, of aninsulating member having two electrodes therein, one extending throughthe outer end of said insulating member and the other communicating witha lateral recess therein, means for connect- 130 'ing a conductor to theend of' said is'. eleclfode, e plunger in eleetfieal communie-ation'with tlie other electrode through. vthe lateral reoess in theinsulating member, engl e spring'linger carrying said plungerand-Confined between insulating Washerssufrounding the first electrode.8. The Combination., in a spark plug or explosive engines, o aninsulating member having two eleetiodes herein, one extending hi'oughthe outer end of said insuletinv member and the other communicating Wien:1 lateral recess herein, and ademe/liable Cep carrying e laterallymovable spyingpi'eesed pluifig'er for Contacting with the seem ondelectrode.

9. rThe combinaion, in a spall plug lei explosive engines, of .miinsulating nembei having two ,elec'i'ocles therein, one extendingthrough ighe outer end of seid insulating I trede, and means eaiiiecl bythe first eleetrede foi1 ieaining said cup in position ai; the outei'enel of lie pluv.

ln testmonj7 whereof, have signed my naine to his specification, in thepresence of 'two subscribing witnesses.

11Witnesses "vn Biani-)nin HLTGN D. TURNER.

